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PpGpp
(p)ppGpp, guanosine pentaphosphate and tetraphosphate, also known as the "magic spot" nucleotides, are alarmones involved in the stringent response in bacteria that cause the inhibition of RNA synthesis when there is a shortage of amino acids. This inhibition by (p)ppGpp decreases translation in the cell, conserving amino acids present. Furthermore, ppGpp and pppGpp cause the up-regulation of many other genes involved in stress response such as the genes for amino acid uptake (from surrounding media) and biosynthesis. Discovery ppGpp and pppGpp were first identified by Michael Cashel in 1969. These nucleotides were found to accumulate rapidly in ''Escherichia coli'' cells starved for amino acids and inhibit synthesis of ribosomal and transfer RNAs. It is now known that (p)ppGpp is also produced in response to other stressors including carbon and phosphate starvation. Historically, literature surrounding (p)ppGpp have given conflicting findings and information on its role in bacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PpGpp
(p)ppGpp, guanosine pentaphosphate and tetraphosphate, also known as the "magic spot" nucleotides, are alarmones involved in the stringent response in bacteria that cause the inhibition of RNA synthesis when there is a shortage of amino acids. This inhibition by (p)ppGpp decreases translation in the cell, conserving amino acids present. Furthermore, ppGpp and pppGpp cause the up-regulation of many other genes involved in stress response such as the genes for amino acid uptake (from surrounding media) and biosynthesis. Discovery ppGpp and pppGpp were first identified by Michael Cashel in 1969. These nucleotides were found to accumulate rapidly in ''Escherichia coli'' cells starved for amino acids and inhibit synthesis of ribosomal and transfer RNAs. It is now known that (p)ppGpp is also produced in response to other stressors including carbon and phosphate starvation. Historically, literature surrounding (p)ppGpp have given conflicting findings and information on its role in bacte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stringent Response
The stringent response, also called stringent control, is a stress response of bacteria and plant chloroplasts in reaction to amino-acid starvation, fatty acid limitation, iron limitation, heat shock and other stress conditions. The stringent response is signaled by the alarmone (p)ppGpp, and modulates transcription of up to 1/3 of all genes in the cell. This in turn causes the cell to divert resources away from growth and division and toward amino acid synthesis in order to promote survival until nutrient conditions improve. Response In ''Escherichia coli'', (p)ppGpp production is mediated by the ribosomal protein L11 (''rplK'' resp. ''relC'') and the ribosome-associated (p)ppGpp synthetase I, RelA; deacylated tRNA bound in the ribosomal A-site is the primary induction signal. RelA converts GTP and ATP into pppGpp by adding the pyrophosphate from ATP onto the 3' carbon of the ribose in GTP, releasing AMP. pppGpp is converted to ppGpp by the ''gpp'' gene product, releasing Pi. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alarmone
An alarmone is an intracellular signal molecule that is produced in bacteria, chloroplasts, and a slim minority of archaea reacting to harsh environmental factors. They regulate the gene expression at transcription level. Alarmones are produced in high concentrations when harsh environmental factors occur in bacteria and plants, such as lack of amino acids, to produce proteins. Stringent factors take uncharged tRNA and convert it to an alarmone. Guanosine-5'-triphosphate (GTP) is then converted to 5´-diphosphate 3´-diphosphate guanosine (ppGpp (p)ppGpp, guanosine pentaphosphate and tetraphosphate, also known as the "magic spot" nucleotides, are alarmones involved in the stringent response in bacteria that cause the inhibition of RNA synthesis when there is a shortage of amino acids. ...), the archetypical alarmone. ppGpp will bind to RNA polymerase β and β´ subunits, changing promoter preference. It will decrease transcription of rRNA and other genes but will increase tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphosphate
Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate esters ADP and ATP are involved in energy storage. A variety of polyphosphates find application in mineral sequestration in municipal waters, generally being present at 1 to 5 ppm. GTP, CTP, and UTP are also nucleotides important in the protein synthesis, lipid synthesis, and carbohydrate metabolism, respectively. Polyphosphates are also used as food additives, marked E452. Structure Image:Triphosphorsäure.svg, Structure of triphosphoric acid Image:Polyphosphoric acid.svg, Polyphosphoric acid Image:Trimetaphosphat.svg, Cyclic trimetaphosphate Image:Adenosindiphosphat protoniert.svg, Adenosine diphosphate (ADP) The structure of tripolyphosphoric acid illustrates the principles which define the structures of polyphosp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SpoT
Spot or SPOT may refer to: Places * Spot, North Carolina, a community in the United States * The Spot, New South Wales, a locality in Sydney, Australia * South Pole Traverse, sometimes called the South Pole Overland Traverse People * Spot (producer), the house producer and engineer for the label SST Records * Spot (rapper) * Spot Collins (1922-1996), American football player and coach * Jerry Chamberlain (known as "Spot"), the guitarist for the rock group the Swirling Eddies * Scott Draves (known as "Spot"), digital artist and VJ * Moondog Spot, a ring name for professional wrestler Larry Booker Advertising * Radio spot, an over-the-air advertisement * TV spot, a televised advertisement * Underwriting spot, an announcement made on public broadcasting outlets, especially in the United States, in exchange for funding Animals * Spot, a dog that remained faithful after his master's death, described in the List of individual dogs * Spot Fetcher, a dog owned by U.S. President George ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RRNA
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins by mass. Structure Although the primary structure of rRNA sequences can vary across organisms, base-pairing within these sequences commonly forms stem-loop configurations. The length and position of these rRNA stem-loops allow them to create three-di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exopolyphosphatase
Exopolyphosphatase (PPX) is a phosphatase enzyme which catalyzes the hydrolysis of inorganic polyphosphate, a linear molecule composed of up to 1000 or more monomers linked by phospho-anhydride bonds. PPX is a processive exophosphatase, which means that it begins at the ends of the polyphosphate chain and cleaves the phospho-anhydride bonds to release orthophosphate as it moves along the polyphosphate molecule. PPX has several characteristics which distinguish it from other known polyphosphatases, namely that it does not act on ATP, has a strong preference for long chain polyphosphate, and has a very low affinity for polyphosphate molecules with less than 15 phosphate monomers. PPX plays an important role in the metabolism of phosphate and energy in all living organisms. It is especially important for maintenance of appropriate levels of intracellular polyphosphate, which has been implicated in a variety of cellular functions including response to stressors such as deficiencie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rtp Protein
RTP may refer to: Organisations * Rádio e Televisão de Portugal, the Portuguese public broadcasting corporation * Royal Thai Police, the national police force of Thailand * RacingThePlanet, an organizer of endurance foot-races * Rally of the Togolese People, a former political party in Togo Science and technology * Radiation treatment planning, in radiotherapy * Reinforced thermoplastic pipe, a high pressure pipe * Rapid thermal processing, in semiconductor production * Round-the-pole flying, of model aircraft Computing * Real-time Transport Protocol, for delivering audio and video over IP networks * Reliable Transport Protocol, a Cisco protocol used by Enhanced Interior Gateway Routing Protocol * Rendezvous and Termination Protocol, part of the PARC internetwork protocol suite Other uses * Recreational Trails Program, in the United States * Red de Transporte de Pasajeros, in Mexico City, Mexico * Regional Transportation Plan, in the United States * Registered Teacher Programm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substrate (biochemistry)
In chemistry, the term substrate is highly context-dependent. Broadly speaking, it can refer either to a chemical species being observed in a chemical reaction, or to a surface on which other chemical reactions or microscopy are performed. In the former sense, a reagent is added to the ''substrate'' to generate a product through a chemical reaction. The term is used in a similar sense in synthetic and organic chemistry, where the substrate is the chemical of interest that is being modified. In biochemistry, an enzyme substrate is the material upon which an enzyme acts. When referring to Le Chatelier's principle, the substrate is the reagent whose concentration is changed. ;Spontaneous reaction : :*Where S is substrate and P is product. ;Catalysed reaction : :*Where S is substrate, P is product and C is catalyst. In the latter sense, it may refer to a surface on which other chemical reactions are performed or play a supporting role in a variety of spectroscopic and microscop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleoside Triphosphate
A nucleoside triphosphate is a nucleoside containing a nitrogenous base bound to a 5-carbon sugar (either ribose or deoxyribose), with three phosphate groups bound to the sugar. They are the molecular precursors of both DNA and RNA, which are chains of nucleotides made through the processes of DNA replication and transcription. Nucleoside triphosphates also serve as a source of energy for cellular reactions and are involved in signalling pathways. Nucleoside triphosphates cannot be absorbed well, so they are typically synthesized within the cell. Synthesis pathways differ depending on the specific nucleoside triphosphate being made, but given the many important roles of nucleoside triphosphates, synthesis is tightly regulated in all cases. Nucleoside analogues may also be used to treat viral infections. For example, azidothymidine (AZT) is a nucleoside analogue used to prevent and treat HIV/AIDS. Naming The term nucleoside refers to a nitrogenous base linked to a 5-carbon suga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Polymerase
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that synthesizes RNA from a DNA template. Using the enzyme helicase, RNAP locally opens the double-stranded DNA so that one strand of the exposed nucleotides can be used as a template for the synthesis of RNA, a process called transcription. A transcription factor and its associated transcription mediator complex must be attached to a DNA binding site called a promoter region before RNAP can initiate the DNA unwinding at that position. RNAP not only initiates RNA transcription, it also guides the nucleotides into position, facilitates attachment and elongation, has intrinsic proofreading and replacement capabilities, and termination recognition capability. In eukaryotes, RNAP can build chains as long as 2.4 million nucleotides. RNAP produces RNA that, functionally, is either for protein coding, i.e. messenger RNA (mRNA); or n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
